The invention relates to a viewfinder system for a digital camera that comprises a main optical path for projecting an outside scene image onto a light sensitive area facility, which facility determines a user field, and an optical extraction path for through mirror-operation extracting a fraction of said outside scene image onto a viewer optical path, and wherein said viewer optical path comprises a first mask for inserting a negative delineating outline into a viewer field and a second mask for inserting a positive delineating outline into the viewer field, both said first and second masks corresponding to said user field, such as being recited in the preamble of claim 1.
Digital cameras are abounding for amateur as well as for professional applications, for still pictures as well as for digital cinematographic applications. The organization of the light-sensitive area will determine the size of the image and/or the part of the outside scene that is available for a user application, such as in the form of a user field. Pixels outside the size of the user field will not be taken further into account. The viewer image is based on a fraction of the intensity of the relevant pixels. Just as the main optical path, the viewer field can have a particular size, that however can in principle be different from the size of the user field.
Now, the actual scene can count both elements that must appear in the user field, and also other elements that may not appear in the user field. Nevertheless, such other elements are often provided intentionally near the scene for realizing certain effects that may relate to the image itself (such as lighting apparatus or an air-fan to mimick winds and the like) or to other aspects of the scene such as audio (microphone dollies and the like). The camera user will want to see such elements in the viewer field without letting them intrude into the scene image proper as determined by the user field. Thus, for optimum discrimination, the representation of the user field is delimited by a mask that will often be just a framing line or even part of such framing line, such as by indicating only the corners of the frame.
Now, for optimum visibility, in lighter scenes the frame should be relatively darker, or negatively delineated, whereas in darker scenes the frame should preferably be relatively lighter, or positively delineated. The activation of the two frame versions could be simultaneously or alternately, such as by time division. Generally, the two masks are produced in or by respective separate facilities.
Now, in various situations, the frame size should allow adapting, such as being governed by a standard organization for transmission or storage, by a more or less arbitrary user choice, by a size and format (A, B, etcetera) of the paper on which the image would ultimately be printed or otherwise hard-copied, or by other considerations.
Prior art, in U.S. Pat. No. 6,088,545 to Abe et al., has proposed the use of hardware diaphragms for both positive and negative delimiting of the scene field. The present invention has recognized the great usefulness that is brought about by driving the size of at least one of the masks by an electronic facility on the basis of pixel-wise driving.